The fall of Mukalla the capital of Yemen's largest province, Hadramawt highlighted how al-Qaida is expanding its foothold in Yemen, taking advantage of the turmoil as a Saudi-led coalition backing the country's beleaguered president tries to fend off a takeover by Shiite rebels.
Mukalla's fall came as the rebels, known as Houthis, made dramatic advances in one of the main strongholds of the president's loyalists, the southern city of Aden. The rebels broke into the center of Aden and briefly captured a presidential palace in the city.
Al-Qaeda in the Arabian Peninsula, as the terror network's branch in Yemen is named, has been benefiting from the turmoil ever since the Houthis first surged from their northern strongholds last year to take over the capital, Sanaa, and much of the north.
Around the country, some Sunni tribal fighters have been making alliances with al-Qaida to fight the rebels, who adhere to the Zaydi branch of Shia Islam.
But the capture of Mukalla was a startling advance. The city lies 300 miles northeast of Aden along the Arabian Sea coast in large but sparsely populated Hadramawt. The militants fanned out along major roads leading into Mukalla on Thursday and took over the city's presidential palace, government agencies and the local Central Bank branch.